Valinomycin is an antibiotic which acts as a potassium (K+) ionophore. Induces K+ conductivity in cell membranes. Also active in vitro against Mycobacterium tuberculosis, and as an apoptosis inducer.

Valinomycin is used diagnostically in ion selective electrodes because of its preferential ability to conduct K+ across the electrodes membrane. Valinomycin induced stimulation of mitochondrial energy dependent reversible swelling, supported by succinate oxidation, cytochrome c (cyto-c) and sulfite oxidase (Sox) (both are present in the mitochondrial intermembrane space (MIS)) are released outside.Valinomycin also inhibits hyphal growth in other dimorphic fungi, Candida tropicalis and Aureobasidium pullulan. It affects the morphology of Candida albicans.